Cheating generally refers to a centre forward loitering behind the defence in an offside position as general play goes on with the intention of then nipping back onside only as the ball is played forward. It is a pain in the arse as a centre back as generally you want your centre forward in front of you where you can see him. Means you spend the entire game having to have eyes in the back of your head as you attempt to hold a higher line and keep him offside or at the very least stop him from dropping your defensive line back to your own penalty box.